It can also hit what's called antenna molecules.
So antenna molecules are other types of chlorophyll, and actually other types of molecules. They vibrate their way, eventually, to chlorophyll A. So I got very excited about the idea of oxidizing water.
I don't like using the word dark reaction because it actually occurs while the sun is outside. Where literally, so here you have a huge concentration of hydrogen protons. And I go into detail on this when I talk about respiration. As they go into lower energy states, that's used to drive, literally, pumps that allow hydrogen protons to go from the stroma to the lumen. They want to-- I guess you could call it-- chemiosmosis. Well, if we're talking about non-cyclic oxidative photophosphorylation, or non-cyclic light reactions, the final electron acceptor.
It's actually occurring simultaneously with the light reactions. So they'll want to go back into the stroma from the lumen. And that turns, literally mechanically turns, this top part-- the way I drew it-- of the ATP synthase. It puts ADP plus phosphate groups together to produce ATP. And I'm going to go into more detail in a second. They want to go back into the stroma and then that drives ATP synthase. ATP synthase to essentially jam together ADPs and phosphate groups to produce ATP. So after that electron keeps entering lower and lower energy states, the final electron acceptor is NADP plus.
Each plant cell will contain 10 to 50 chloroplasts. But you'll have 10 to 50 of these chloroplasts right here. Which means you're really taking electrons away from oxygen. The only place that we know that an oxidation agent is strong enough to do this is in photosystem II.
I make them green on purpose because the chloroplasts contain chlorophyll. But remember, they're green because they reflect green light and they absorb red and blue and other wavelengths of light. So it's a very profound idea, that normally electrons are very happy in water. That's why we even call it oxidizing, because oxygen is very good at oxidizing things.
And of course, these cells have nucleuses and DNA and all of the other things you normally associate with cells. Because that's what we tend to associate it with. But anyway, we'll talk more about that in detail. Or at least on a chemistry level, something profound is happening. And in the entire biological kingdom, the only place where we know something that is strong enough of an oxidizing agent to oxidize water, to literally take away electrons from water.
And it's the same thing, because when you gain a hydrogen atom, including its electron, since hydrogen is not too electronegative, you get to hog its electron. Each of these membrane-bound-- you can almost view them as pancakes-- let me draw a couple more. And just to get all of our terminology out of the way, a stack of several thylakoids just like that, that is called a grana. So you can kind of imagine it donates two hydrogen protons and two electrons to replace the electron that got excited by the photons.
So this is both gaining a hydrogen and gaining electron. So before we dig a little deeper, I think it's good to know a little bit about the anatomy of a plant. So plant cells actually have cell walls, so I can draw them a little bit rigid. And then within the chloroplast itself, you have these little stacks of these folded membranes, These little folded stacks. Maybe we have some over here, just so you-- maybe you have some over here, maybe some over here. Because that electron got passed all the way over to photosystem I and eventually ends up in NADPH.
But then you can use that to build up glucose or any other carbohydrate. So the exact same-- let me see if I can draw that ATP synthase here. We're using photons to excite electrons in chlorophyll.
So, with that said, let's try to dig a little bit deeper and understand what's actually going on in these stages of photosynthesis. The light-dependent reactions and then you have the light independent reactions. You might remember ATP synthase looks something like this. So these hydrogen protons are going to make their way back. And as they go down the gradient, they literally-- it's like an engine. As those electrons get passed from one molecule, from one electron acceptor to another, they enter into lower and lower energy states.